JPH0245246B2 - JIKITEEPUNOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetic tape.

Usually, in a film in which a metal layer is formed on a plastic substrate by means such as vapor deposition, the plastic substrate deforms into a circular shape with the metal layer side facing inside or outside due to the difference in thermal expansion coefficient between the plastic and metal. . This state is called curl. When a film in which a metal layer is formed on a plastic substrate is used as a magnetic tape as described above, it cannot be put to practical use if it is curled, and must be flattened before use.

Conventionally, in order to flatten a curl in a vapor-deposited magnetic tape, the magnetic tape is brought into contact with a heated roll, and the plastic substrate is shrunk and flattened. At this time, since the temperature is raised above the glass transition point of the plastic substrate, transfer of the surface shape of the heating roll occurs. Furthermore, there were problems such as the generation of wrinkles due to heat shrinkage during the cooling process of the magnetic tape.

The transfer of the shape from the heating roll is harmful as modulation noise in the short wavelength region in magnetic recording. Further, the wrinkles caused by the heat shrinkage cause long-period output fluctuations, which is harmful.

The present invention eliminates the conventional drawbacks such as the transfer of the shape from the heating roll by a technique of flattening a curled magnetic tape while holding the magnetic tape in the air.

Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment of the magnetic tape manufacturing method of the present invention will be described with reference to the drawings. The figure shows a method of processing a film for vapor-deposited magnetic tape, in which a magnetic film is vapor-deposited on a plastic substrate. The width of this film is, for example, 1000 mm. In the figure, 1 is an unwinding roll (original film) wrapped with film.
This is the unwinding part. The film on the unwinding roll 1 is made of a plastic substrate,
An example of such a material is polyethylene terephthalate. 2 is a nip roll, which is designed to nip the film and feed it out at a constant speed rotation. 3 is a guide roll made in the middle. The unwinding roll 1 operates to maintain a constant tension while being nipped by the nipping roll 2.
4 and 5 are nozzles for floating the film in the air. The nozzle 4 is composed of a portion configured to blow out hot air from below and a portion configured to suck the blown hot air for circulation. The nozzle 5 is an upper nozzle portion having a structure similar to that of the lower nozzle 4. 6 is a heating part that generates hot air from the nozzle 4 below;
is the part of the blower that generates the pressure for the lower nozzle 4. In order to reuse the warm air once blown out from the nozzle, the blower 7 takes in the sucked air and some new air and uses it. 8 is a heating part of the upper nozzle 5, and 9 is an upper blower. The structure of this upper nozzle 5 is similar to that of the lower nozzle 4. Furthermore, these nozzles 4 and 5 are constructed so that the temperature of the hot air at the film entry and exit parts can be adjusted.

Reference numeral 10 is a guide roll exiting the heating section, and also serves as a tension detection roll. Reference numeral 11 denotes a nip roll. This nip roll 11 nips the film, rotates while being controlled by a tension signal from the detection roll 10, and maintains the tension of the heated portion of the film constant. Reference numeral 12 denotes a winding section that winds up the film with a constant tension, and winds up the flattened film.

In the apparatus configured as described above, the film wound around the unwinding roll 1 has just been coated with a magnetic film and is curled. The cause of curling is due to the difference in thermal expansion coefficient between the plastic substrate and the metal film that make up the film. In other words, the metal film is deposited on a portion of the plastic substrate that is held so that the temperature does not rise.
The metal film is cooled during film formation. At this time, since the degree of thermal contraction of the metal film upon cooling is different from that of the plastic substrate, curling occurs in the film. At this time, the film is curled into a circular shape with the magnetic film inside. Curling occurs equally in both the longitudinal and width directions of the film,
When used as a magnetic tape, the main problem is curling in the width direction.

Such curling of the film is flattened when the film passes between the nozzles 4 and 5 that generate hot air. The principle of flattening is to flatten the plastic substrate by shrinking it by the same amount as the shrinkage of the magnetic film. In this case, the shrinkage effect of plastic due to heating is utilized. That is,
Plastic shrinkage depends on temperature and tension, and control of these factors is important. The device is provided with nozzles 4 and 5 for heating the film, and nip rolls 2 and 11 for applying tension.

The appropriate heating temperature here is a temperature higher than the glass transition point of the plastic, but in the present invention, since the shrinkage effect in the floating state is utilized, the maximum temperature is approximately 10°C lower than the softening point temperature. It is. The film is heated approximately 20°C lower than the maximum temperature at the entrance between nozzles 4 and 5, and after being heated linearly to the maximum temperature at the center of nozzles 4 and 5, the film is kept at a constant temperature and heated between nozzles 4 and 5. At the exit, the temperature is gradually and linearly lowered by 30°C below the maximum temperature.

As an example of the configuration of the hot air nozzles 4 and 5, the furnace length is 5 m, the heat removal section at the inlet is 1 m, the highest temperature section at the center is 3 m at 110°C for PET, and the cooling section at the outlet is 2 m. The length is .

In the method of the above-mentioned example, the film whose curls have been flattened has less shape transfer when evaluated as a magnetic tape, and has a recording wavelength of around 10 μm compared to the conventional film treated with a heated roll. Modulation noise was improved by 2 to 3 dB.

As explained above, the magnetic tape manufacturing method of the present invention is characterized by heat-treating the magnetic tape while applying tension to the magnetic tape in the air, and it is possible to obtain a flat, high-quality magnetic tape with less noise. , has high industrial utility value.

[Brief explanation of the drawing]

The figure is a diagram showing an example of the configuration of an apparatus used when implementing the magnetic tape manufacturing method of the present invention. 2, 11... Nippro roll, 3, 10... Guide roll, 4, 5... Nozzle, 6, 8... Heating section,
7, 8...Blower.

Claims (1)

[Claims] 1. A film consisting of a plastic substrate and a magnetic layer formed on the plastic substrate is transported while floating in the air, and while tension is applied to the film during the transport, the temperature is lowered from the glass transition temperature of the plastic substrate. A method for manufacturing a magnetic tape, comprising the step of heat treatment at a temperature 10 degrees lower than the softening point temperature of the plastic substrate.